Specifically, somewhere in your code (the filename and line number should also be included in your error message), you’re trying to call the function `script_enqueuer`, but that function doesn’t exist (or hasn’t been loaded; at least, not by the time it’s called).

If it’s in a plugin, you can probably find out which one fairly easily by checking which file the error is occurring in. That way, you don’t have to use trial-and-error to find it.